Centrifugal switch mechanism



Jan. 30, 1968 J YCARI I 3,366,757

CENTRIFUGAL SWITCH MECHANISM Fi led March 28, 1966 cmcun" INVENTOR ALVIN J. CARL! fi y: &4 M

ATTORNEYS United States Patem so 3,366,757 CENTRIFUGAL SWITCH MECHANISM Alvin J. Carli, Sebring, Ohio, assignor to Consolidated Electronics Industries Corp., a corporation of Delaware Filed Mar. 28, 1966, Ser. No. 537,764 11 Claims. (Cl. 200-80) ABSTRACT OF THE DICLOSURE The disclosure relates to a simple and reliable centrifugal switch wherein a Weight is guided between a plate and an arm, both normal to the axis of a rotatable hub. A spring urges the weight radially inwardly into engagement with a conductive metal sleeve to be grounded to the frame of the motor or other mechanism with which the switch is used. Upon rotation above a given rate, centrifugal force moves the weight radially outwardly to break the electrical connection.

The invention relates in general to a torque switch mechanism and more particularly to a switch actuated by centrifugal force or the torque load connected to the rotating part of the switch mechanism.

The invention may be used in a switch mechanism in connection with an electric motor, for example, wherein it is desirable to control the energization to the motor in accordance with the load on the motor. If the load should exceed a predetermined maximum and tend to stall the motor, then the motor will be deenergized so as to protect personnel operating or near the load, or also to protect the load, the motor or circuit.

An object of the invention is to provide a centrifugally operated switch which is rugged yet simple and dependable.

Another object of the invention is to provide a torque switch mechanism which may be incorporated in conjunction with a friction clutch and which utilizes several of the parts of the friction clutch.

Another object of the invention is to provide a centrifugal switch mechanism having radially slidable weight responsive to centrifugal force and with this weight engageable with a metal sleeve insulated from a rotatable hub on which it is mounted.

Another object of the invention is to provide a centrifugal switch mechanism With a minimum of parts and with the parts made in a most economical manner and with the parts capable of assembly in a minimum time.

Another object of the invention is to provide a centrifugal swtich mechanism wherein the parts are simple and rugged and will not break or wear out for many tens of thousands of operations.

The invention may be incorporated in a centrifugal switch mechanism for use with a frame comprising, in combination, :a rotatable metal hub, an insulator bushing surrounding said hub, a metal sleeve on said insulator bushing and journalled for rotation relative to said hub, a circular metal plate fixed on the hub generally normal to the axis of said hub, an arm fixed on said hub and extending generally radially from said hub, a lever extending generally radially from and fixed to said metal sleeve, a weight having a portion disposed between said arm and said metal plate to be radially slidable and having an inner end engageable with said metal sleeve, a spring urging said weight radially inwardly toward said metal sleeve, an electrical terminal onsaid lever, insulator means acting between the outer end of said lever and a frame to hold said. lever rotatively fixed, said weight moving radially away from said metal sleeve to be-electrically disengaged therefrom upon rotation of said hub, metal plate, arm and weight, and electrically engaging said metal sleeve upon said hub slowly to a predetermined rotational speed to establish an electrical connection between said terminal and said hub.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a combined schematic diagram and 10ngitudinal sectional view through a motor and switch mechanism embodying the invention;

FIGURE 2 is a sectional view of 1; and

FIGURE 3 is a sectional view on line 3-3 of FIG- URE 1.

The invention may be incorporated in connection with a motor 12. This motor, by Way of example, may be used with a garage door operator 11 operating through linkage means to open and close a door 13. The door has been shown as an overhead type of garage door which may move upwardly to an open position and downwardly to a closed position. This movement may be on a track 14. A guideway 15 may guide movement of a carriage 16 which moves longitudinally thereof and through a link 17 causes opening and closing movements of the door 13.

The motor 12 has a stator 20 and a rotor 21 with a first end 22 of the rotor 21 being at the right as viewed in FIG- URE 1. The rotor 21 is journalled in a radial bearing 23 in the stator 20 and the entire rotor 21 has a hollow shaft 24. I

A friction clutch includes a circular drive member 27 and a circular disc driven member or plate 28. Friction material 29 may be carried in the drive member 27. The drive member 27 is fixedly carried on the hollow shaft line 2--2 of FIGURE 24 by a key 30 for rotation therewith. The driven member 28 also includes a hub 31 fixedly keyed at 32 to a shaft extension 33 of a worm 34. This shaft extension 33 extends through and is journalled in the rotor 21 and carries a thrust bearing 35 for engagement with the end of the hollow rotor shaft 24. The hub 31 and disc driven member 28 are fixed to rotate together.

A coil compression clutch spring 36 surrounds the outer end of the shaft extension 33 and a nut 37 and a lock nut 38 engages a threaded end 39 on the shaft extension 33 to cause variable compression of the clutch spring 36. This causes variable friction engagement between the drive and driven members 27 and 28 of the clutch.

The worm 34 engages nut means 40 to cause longitudinal traverse of this nut means which is connected by a link 41 to the carriage 16 to cause the door-13 to be opened and closed upon proper rotational operation of the rotor 21.

The torque or centrifugal switch mechanism 44 includes some of the parts of the friction clutch 27, 28. Specifically it includes the circular metal plate 28 which is the driven member of the clutch and includes the hub 31. The hub 31 has first and second shoulders 45 and 46. The hub also has an enlarged head 47, a cylindrical portion 48 and a reduced neck 49. This reduced neck is of non-circular shape as shown in FIGURE 2. The circular plate '28 has a correspondingly shaped non-circular aperture 50 to be received on the reduced neck 49. An arm 53 has a first end 54 with a non-circular aperture also received over this reduced neck 49 to be fastened thereto. Arm 53 also has a second end 55 extending generally radially from 'T the hub 31. The reduced neck 49 is staked at 56 to retain the metal plate 28 and arm 53 in place and fixed to the hub 31.

31. This insulator bushing 58 is axially restrained in place between the annular shoulder 45 and the arm 53. The insulator bushing has first and second shoulders 59 and 60 which face in opposite directions and are near the two axial ends of this bushing. A metal sleeve 62 surrounds the outer periphery of this insulator bushing 58. The metal sleeve has first and second flanges 63 and 64, respectively. The first flange 63 extends outwardly and is generally coplanar with the shoulder 59 on the insulator bushing 58. The second flange 64 is turned inwardly and engages the shoulder 60 on the insulator bushing 58. A lever 66 extends generally radially from the hub 31. The lever has first and second ends 67 and 68 with the first end being a hooked end riveted by rivets 69 to the flange 63 of the metal sleeve 62. Also this lever 66 overlies and engages the annular shoulder 59 on the insulator bushing 58 so as to fixedly attach the combination of metal sleeve 62 and lever 66 to the insulator bushing 58 and also to restrin this combination of metal sleeve 62 and lever 66 in both axial directions. This prevents either the sleeve 62 or lever 66 from touching the hub 31, arm 53, or metal Plate 28, which are grounded to the frame of the motor 12.

The lever 66 has an S-bend 70 between the first and second ends thereof and an electrical terminal 71 is provided on the axially parallel portion of this lever 66. This electrical terminal may be a self-tapping screw to attach a Wire lug 72 to this lever 66. The second end 68 of lever 66 has a radially elongated aperture 73 in which an insulator sleeve 74 is disposed. The axis of this insulator sleeve 74 is parallel to the axis 75 of the bushing 31 so that it may readily slide over a fixed stud 76 at the same time that the hub 31 is axially assembled onto the shaft extension 33. This fixed stud 76 may conveniently be one of the motor bolts which hold the end bells onto the motor 12.

The arm 53 has an S-bend 79 between the first and second ends thereof. The second end 55 of the lever has an aperture 80. This aperture is generally radial and is bounded by surfaces 81 and 82 which are parallel to a radius from axis 75. A weight 85 is generally T-shaped in peripheral cross section, as Seen in FIGURE 3, and has first and second portions 86 and 87. The first portion 86 may be the body of the T and the second portion 87 may be the cross bar on the T. The first portion 86 has two parallel surfaces disposed between the two surfaces 81 and 82 of the radial aperture 80. This restrains the weight 85 in a peripheral direction relative to the arm 53 so that the weight 85 will rotate with arm 53. The second portion 87 of the weight also has two parallel surfaces disposed between the generally parallel surfaces of the plate 28 and arm second end 55. This restrains the weight 85 in an axial direction and hence the weight 85 is only radially slidable in the aperture 80.

The weight 85 has a radial aperture 89 at the outer end thereof receiving one end of a coil compression spring 90. The other end of this spring 90 engages a shoulder 91 on the outer end of arm 53 and also embraces a tongue 92 extending radially inwardly from this shoulder 91. 7

It will be observed in FIGURE 1 that the aperture 56 in the circular plate 28 is eccentrically positioned. The

' arm 53 and weight 85 are positioned at the radially shortest dimension of the circular plate 28, opposite the largest radial dimensions of this plate 28 so that the weight 85 and arm 53 are counterbalanced.

FIGURE 1 shows an electrical control circuit 94 which has a voltage source input terminal 95 and control terminals 96 and 97. The electrical control circuit 94 is also connected to the motor 12 by energization conductors 98 to supply energization for forward and reverse conditions of the motor 12. The control terminal 96 is connected by a conductor 99 to the terminal 71 and the control terminal 97 is connected by a conductor 100 to be grounded to the frame of the motor 12 at any 43, convenient location such as the motor bolt 76. The electrical control may be similar to that shown in Patent No. 2,992,378, for example, entitled Electrical Control Circuit for Door Operators, issued July 11, 1961.

Operation The electrical control circuit 94 may be controlled in any suitable manner to provide energization to the motor 12 to either raise or lower the door 13. FIGURE 1 shows the door closed and upon energization of the motor 12 to raise the door, the motor as it comes up to speed causes opening of the torque switch mechanism 44. This may conveniently be at about one-half speed of the motor. The clutch 27, 28 is adjustable as to the point at which it will slip by variable compression of the spring 36. Generally the clutch will be adjusted to move the door under normal operating conditions but to slip upon a definite overload so that should the door strike some obstacle or the down travel limit, the clutch will slip. Under such condition with the door stalled, this stops the worm 34, hub 31 and clutch plate 28. As the driven clutch plate 28 slows to a stalling point, some predetermined speed will be reached, for

. example, about one-half motor speed, to close the torque switch mechanism 44. At full speed of the motor the weight 85 will be centrifugally forced outwardly against the urging of spring 90. Now upon deceleration the weight 85 will be urged inwardly by spring 90 to engage the metal sleeve 62. Because plate 28, hub 31, and weight 85 are grounded this will ground the metal sleeve 62 and terminal 71. The control circuit 94 is thus c011- ditioned to deenergize the motor 12. Thus the use of this torque switch mechanism 44 promptly deenergizes the motor 12 and thus prevents the motor from being overloaded by the stalled condition of the door 13.

The metal hub 31 has both shoulders 45 and 46 facing in the same direction and with no undercuts in longitudinal cross section so that this hub may be made by a simple machining operation or preferably may be made from sintered iron, for example, in a simple two part mold which separates longitudinally. This hub 31 also may be oil impregnated so that it may slide on shaft extension 33 as the clutch disc 29 wears. The clutch plate 28 and arm 53 are simple stampings of sheet steel, for example. Also the clutch plate 28 and hub 31 perform functions in both the clutch members 27, 28 and the torque switch mechanism 44.

The insulator bushing 58 has the two shoulders 59 and 60 facing in opposite axial directions and hence this bushing also may be made from a simple molded part in only a two part mold for example. This mold may part .in a longitudinal direction. The metal sleeve 62 may be made of any convenient metal such as brass or aluminum and may be a stamping or may be drawn. The first flange 63 need not be annular, but it does provide a tab to which the lever 66 is fixedly attached so that this combination of metal sleeve and lever 66 is axially restrained in both directions on the insulator bushing 58. This assures that the metal sleeve will not be grounded against the hub 31, arm 53 or metal plate 28 except when the switch itself is closed. Further the slight slippage between the weight 85 and metal sleeve 62, each time the motor is started or stopped, cleans the contact surfaces of the inner end of weight 85 and the outer cylindrical surface of metal sleeve 62.

The staking of hub neck 49 to the metal plate 28 not only holds this plate in place but also holds arm 53 in place. Further this staking establishes arm 53 as a surface normal to axis 75 to axially restrain the insulator bushing 58 between the arm 53 and the annular shoulder 45 on hub 31.

The T shape of the weight 85 and its disposition in the aperture and between arm 53 and plate 28 restrains this weight for all except radial sliding movements. The weight may be made from sintered bronze, for example, in a simple'two part mold separable in a radial direction relative to the disposition of this weight 85. There are no undercuts on this weight 85, as viewed in radial cross section of FIGURE 1 and this permits the weight to be radially slidable and also permits its manufacture in a two part mold. Further the S-bend 79 in arm 53 permits ready assembly of the switch mechanism. The body portion 86 of the weight 85 may be slipped through the radial aperture80 in arm 53 in a direction parallel to axis 75. The spring 90-may then be insertedin aperture 89 and slipped over tongue 92. The spring 90 will then urge the weight inwardly against the S-bend 79 and this will hold the weight 85 and spring 90 in place for this stage of the assembly. The metal sleeve 62 readily slides over the left end of insulator bushing 58 as viewed in FIGURE 1 and then the lever 66 may be riveted in place. Next this sleeve and bushing sub-assembly may be slipped over the left end of the hub 31, the arm and weight subassembly slipped over the reduced neck 49, metal plate 28 put in place and staked at 56. This will complete the assembly of this simple, rugged and reliable torque switch mechanism. When this torque switch is mounted in place on the shaft extension 33, with the key 32 engaging the shaft and hub 31, then the insulator sleeve 74 will also longitudinally be positioned on the motor bolt 76. This will restrain the lever 66 from rotation and thus permit the switch mechanism 44 to properly function.

The torque switch mechanism 44 may be incorporated in a door operator in place of the torque switch shown in Patent 2,954,224, for example. This patent issued Sept. 28, 1960, and is entitled Torque Switch.

111- this aforementioned patent the torque switch had many parts and in the present invention more than half of these parts have been omitted yet the torque switch is every bit as rugged and in fact more reliable by the omission of these many parts. Additionally the torque switch of the present invention is far easier to assemble and can be assembled accordingly in far less than one-half the time. The hub 31 and metal clutch plate 28 are heavy rugged metal members because they are part of the clutch mechanism and must absorb considerable shock from starting and stopping of the garage door.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing descrip tion. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to Without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is: v

1. A centrifugal switch mechanism for use with a frame comprising, in combination, a rotatable metal hub,

an insulator bushing surrounding said hub,

a metal sleeve on said insulator bushing and journalled for rotation relative to said hub,

a metal plate fixed on the hub generally normal to the axis of said hub,

an arm fixed on said hub and extending generally radially from said hub,

a lever extendinggenerally radially from and fixed to I said metal sleeve,

a weight having a portion guided between said arm and said metal plate to be radially slidable and having an inner end engageable with said metal sleeve,

a spring urging said weight radially inwardly toward said metal sleeve,

an electrical terminal on said lever,

insulator means acting between said lever and a frame to hold said lever rotatively fixed,

said weight moving radially away from said metal sleeve to be electrically disengaged therefrom upon rotation of said hub, metal plate, arm and weight, and electrically engaging said metal sleeve upon said hub slowing to a predetermined rotational speed to establish an electrical connection between said terminal and said hub. 1 5 2. A switch mechanism as claimed in claim 1 wherein said hub has first and second shoulders facing in one direction, said bushing being disposed between said first shoulder and said arm, and said metal plate being staked to said hub near said second shoulder.

3. A switch mechanism as claimed in claim 1, wherein said metal sleeve is fixed on said insulator bushing and said insulator bushing being journalled on a cylindrical portion of said hub.

4. A switch mechanism as claimed in claim 1 wherein said insulator bushing has first and second outwardly facing annular shoulders,

said metal sleeve having first and second flanges,

said first flange on said metal sleeve being substantially coplanar with said first shoulder on said insulator bushing and said second flange on said metal sleeve engaging said second shoulder on said insulator bushs,

and said lever being fixedly attached to said first flange on said metal sleeve and also engaging said first shoulder on said insulator bushing to axially restrain the combination of said lever and said metal sleeve relative to said insulator bushing.

5. A switch mechanism as claimed in claim 1 including said metal plate being staked to said hub,

said insulator bushing being disposed between said metal plate and an enlarged end of said hub adjacent, said arm having a mounting portion thereofdisposed between said insulator bushing and said metal plate, the staking of said metal plate to said hub axially restraining said insulator bushing relative to said hub.

6. A switch mechanism as claimed in claim 1 including first and second ends on said arm with said first end fixed to said hub,

two parallel and generally radially extending surfaces on the second end of said arm, said weight having first and second portions with said first portion having generally parallel surfaces slidably engageable with said two surfaces on said arm,

said second portion lying between said arm and said metal plate to restrain said weight in place axially relative to said hub,

said weight having a radial cross section without undercuts to permit free radial sliding movements within limits of said weight relative to said arm and plate part mold separable radially,

and said spring being a coil compression spring disposed between the outer end of said weight and a radial shoulder on said arm to urge the weight radially inwardly toward said metal sleeve.

7. A switch mechanism as claimed in claim 1 including first and second ends on said arm with said first end fixed to said hub,

a radially extending aperture in the second end of said arm, 7 l

said weight having a T-shaped cross section, the head of the T lying between said arm and said metal plate with the base of the T extending through said radial aperture to restrain said weight in place axially and circumferentially relative to said hub,

an aperture in the outer end of said weight,

a tongue disposed in said aperture of said arm,

and said spring being a coil compression spring disposed in said aperture and embracing said tongue to urge the weight radially inwardly toward said metal sleeve.

8. A switch mechanism as claimed in claim 1 wherein said insulator means is an insulator sleeve disposed in a radially elongated hole in the outer end of said lever,

said insulator sleeve extending generally parallel to the and to permit manufacture of said weight in a twoaxis of said hub to slide over a longitudinally parallel fixed stud as said hub is mounted on a rotatable shaft.

9. A switch mechanism as claimed in claim 1 wherein said circular metal plate has an eccentrially positioned aperture therein,

and said arm and weight being radially positioned at the radially shortest dimension of said metal plate to be disposed 180 degrees from the radially largest dimension of said metal plate to counterbalance the mass of said weight and said arm.

10. A centrifugal switch mechanism, comprising, in

combination, a conductive rotatable hub,

an arm having first and second ends with said first end fixed on said hub,

a metal plate having an eccentric aperture fixedly mounted on said hub,

first and second shoulders on said insulator bushing,

a metal sleeve,

a lever extending generally radially from said hub and fixed to said metal sleeve and the combination of said metal sleeve and lever engaging said shoulders on said bushing to restrain the combination of said metal sleeve and lever in both axial directions relative to said bushing,

a radial aperture in said second end of said arm,

a radially slidable weight having a portion disposed in said radial aperture and having a second portion disposed between said metal plate and said arm second end to restrain said weight for essentially only radial sliding movements,

an inner contact end on said weight frictionally slidable on the outer periphery of said metal sleeve,

a spring acting on said arm and urging said weight inwardly toward said metal sleeve,

said eccentric aperture mounting of said metal plate establishing the largest radial dimension of the metal plate 180 degrees from said weight to counterbalance the mass of said weight and arm,

an electrical terminal on said lever for electrical connection tosaid lever and metal sleeve,

and insulator means holding the outer end of said lever rotatively fixed, whereby said hub, plate, arm and weight are rotatable and at a predetermined rotational speed said weight will move radially outwardly to be electrically disengaged from said metal sleeve and whereby upon slowing of the hub the weight at a predetermined rotational speed will contact said metal sleeve to establish an electrical connection between said electrical terminal and said hub.

11. A torque switch mechanism, comprising, in combination, a metal hub having an aperture for fixedly mounting on and rotatable with a rotatable shaft,

first and second shoulders on said metal hub facing in one direction,

a reduced neck of non-circular cross section on said metal hub at one end thereof as an extension from the second shoulder,

an arm having first and second ends,

a non-circular aperture in said first end of said arm surrounding said neck,

a circular metal plate having an eccentric aperture surrounding the reduced neck of said hub outboard of said arm and staked to said hub at said reduced neck to fix said metal plate and arm to said hub, I

an insulator bushing surrounding and journalled on said metal hub and axially retained on said metal hub between said first shoulder and said arm,

first and second annular shoulders on said insulator bushing facing axially in opposing directions near opposite axial ends of said bushing,

a metal sleeve having an outward flange disposed generally coplanar with said first annular shoulder on said bushing,

an inturned flange on said sleeve crimped over said second annular shoulder on said bushing,

a lever extending generally radially from said hub and riveted to said metal sleeve at said outward flange and overlying said first annular shoulder on said bushing to restrain the combination of said metal sleeve and lever in both axial directions relative to said bushan S-bend between said first and second ends of said second end of said arm,

a radially slidable weight disposed in said radial aperture and having a flange portion disposed between said metal plate and said arm second end to restrain said weight for essentially only radial sliding movements,

an inner friction end on said weight frictionally slidable on the outer cylindrical periphery of said metal sleeve,

a coil compression spring disposed between the second end of said arm at the aperture thereof and the outer end of said weight to urge said weight inwardly toward said metal sleeve,

said weight and arm being circumferentially positioned at the radially shortest dimension of the eccentric mounting of said metal plate to have the largest radial dimension of the metal plate 180 degrees therefrom to counterbalance the mass of said weight,

an electrical terminal on said lever for electrical connection to said lever and metal sleeve,

said weight being grounded through said arm, said metal plate and said metal hub,

and an insulator sleeve on the outer end of said lever to be engaged by a member to hold said lever rotatively fixed, whereby said hub, plate, arm and weight are rotatable and at a predetermined rotational speed said weight will move radially outwardly to be electrically disengaged from said metal sleeve and whereby upon slowing of the metal hub the weight at a predetermined rotational speed will contact said metal sleeve to establish an electrical connection between said electrical terminal and ground.

References Cited UNITED STATES PATENTS 2,868,917 l/1959 Maerker ZOO- 2,845,505 7/1958 Jury 200-80 3,095,097 6/1963 Mellow 20080 X 3,206,571 9/1965 Moore 20080 BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. 

